1. Field of the Invention
The present invention relates to a rotation angle detection device for detecting the angle of rotation of an object to be detected by the use of a magnetoresistive member and a magnet.
2. Description of the Related Art
There has hitherto been known a rotation angle detection device in which a permanent magnet is mounted on an end portion of a rotation shaft, and a magnetoresistive sensor is arranged on an axis of the rotation shaft away from the permanent magnet and orthogonal to the rotation shaft, so that it can detect the angle of rotation of the rotation shaft in response to the magnetic flux generated by the permanent magnet in a direction orthogonal to the axis of the rotation shaft (for example, see a first patent document: Japanese patent application laid-open No. 11-94512).
In such a rotation angle detection device, however, there is the following problem. That is, the majority of the magnetic flux generated by the permanent magnet leaks outside an area in which the magnetoresistive sensor is sensitive or responsive, and hence the permanent magnet itself is required to generate a higher magnetic flux density, thus resulting in an increased size and higher cost.